Coiler for reversing hot mills



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W M M 1 mw/W Aug. 31, 1954 A. B. MONTGOMERY COILER FOR REVERSING HOT MILLS 8 Sheets-Sheet 8 Original Filed Feb. 19, 1947 WM w Mm MM M a o 0 m 1 Ma $3252 Patented Aug. 31, 1954 UNITED STATES PATENT OFFICE Continu i n f appli i n Seri l No- 2916 February 19, 1947. This application March 20, 1953, Serial No. 343,568

8 Claims. 1

This invention relates generally to metal rolling apparatus. More particularly it relates to a reversing-type hot rolling mill primarily designed for the rapid. and efficient rolling of hot steel strips. This application is a continuation of application Serial No. 729,604, filed February 19, 1947, now abandoned.

The preferred form of the invention contemplates a reversing rolling mill construction primarily intended for the rolling of hot strips from a maximum thickness, which is suitable for coiling, down to the final or desired thickness of the sheet or strip. It will be obvious to those skilled in the art that the rolling mill construction hereinafter described may, if desired, be incorporated in a rolling mill table embodying suitable rolls for reducing metal from billet thickness to approximately 2 inches in thickness which is too thick for ceiling. The strip so prepared is then rolled in the reversing mill embodying the invention down to a maximum coiling thickness in a flat condition after which further rolling is accompanied by coiling. During flat rolling, certain of the elements of the coiling rolling mill are moved to a position in which the strip may slide along the rolling table in a flat condition and not be coiled in the ceiling furnaces. When the strip is reduced to coiling thickness, the coiling furnaces are used until such time that the thickness of this strip is reduced to the desired dimension, after which the strip is removed from the coiling mill and coiled into suitable form for sale to the trade.

It will be obvious, however, that the shown coiling mill may also he used separate and apart from the billet reducing mill which initially reduces the metal into a plate or sheet of suitable thickness so that i can be rolled in the reversin coiling mill. In such event th bill is roll d to the desired thickness and then is transferred from the billet rolling table to the coiling mill where it is subsequently rolled to the desired thickness. Also. if d ired, he c ilin m m y be placed either above or below the billet rolling mill and, after the strip has reached the desired maximum thickness, suitable gates may be closed for transferring the strip from the billet mill to the coiling rolling mill.

A primary object of the present invention con.- sists in the provision ofl' an improved type of coiling furnace which, together with the other features hereinafter described, serves to operate substantially automatically and which is characterized by novel means for pi kin up an n gaging the free end of the strip so that the same is projected into the coiler furnace.

Further, the present invention contemplates the provision of a coiler furnace construction in which the means for engaging and anchoring the end of the strip is so constructed and arranged that heat losses normally suffered at the end of the strip are reduced to a minimum and scrap losses are thereby correspondingly reduced.

A further object is to provide a hot strip metal rolling mill wherein heat losses due to radiation and convection are maintained at a minimum.

A still further object is to provide suitable heating means whereby the heat of the steel strip which is lost during each rolling operation is evenly replenished to the strip each time that it is passed through the reducing rollers.

The invention contemplates the provision of a coiler-type furnace in which means are provided for maintaining the coiler drum in predetermined stationary position as the end of the strip enters the furnace together with means automatically operating to commence rotation of the coiler drum when the end of the strip has been properly received and anchored therein.

Still another object of the present invention consists in the provision of an improved type of coiler furnace consisting of a refractory base and refractory hood housing the coiler drum and together serving to provide a combustion chamber of such construction and arrangement that heat losses in the said coil strip are reduced to a minimum and that the coil strip on the drum is heated with approximate uniformity around the V periphery and end of the coil.

Still further, the improved coiler furnace contemplates the provision of a coiler roll mounted for vertical movement within the coiler furnace. This coiler roll is adapted to co-operate with the coiler drum to hold the strip tightly engaged therewith until the coiler drum has made at least one complete revolution and includes substantially automatic means for bringing the coiler roll into engagement with the coiler drum.

Still further, the improved coiler furnace contemplates the use of the coiler roll at the end of a run of the strip through the rolling mill for holding the strip tightly about the coiler drum.

Still further, the invention contemplates the provision of a reversing hot strip mill construc tion embodying a novel arrangement and operation of guides for guiding the strip to and from the work rolls. In construction of this general type, it has heretofore been conventional to utilize so-called taper guides which have progressively decreasing spacing between them. The present invention, however, contemplates the use of automatically adjustable guides which at all times are maintained substantially parallel.

The improved construction contemplates automatic means for moving the guides on the entering side of the work rolls closer together and the guides on the leaving side further apart thereby assuring precise feeding of the strip through the work rolls. When the strip is fed through the work rolls in the opposite direction, the position of the guides is altered so that the guides on the entering side of the rollers are moved into guiding position and the guides on the exit side of the rollers, which during the preceding operation were inlet guides, are now moved to further open position.

Still further, the invention contemplates the provision for manually positioning the guides in order that the same may be accurately and precisely adjusted for the rolling of strips of various widths, this adjustment being made entirely independent of the automatic control of these guides which operate upon reversal of the mill.

Yet another advantage, object and feature of the present invention resides in the system of substantially automatic control which electrically co-ordinates the various novel and improved features of the mill where the mill can be easily and precisely controlled. These controls are coordinated in such a way that the mill, while not being entirely automatic in operation, relieves the operator of many of the detailed controlling functions.

Other objects of this invention will be apparent from the specification and the claims appended thereto.

In the drawings which form a part of this specification and in which the same reference characters are used to designate the same elements in the various figures,

Figure 1 and Figure 2, when placed end to end with Figure 2 at the right end of Figure 1, show in plan view the hot rolling coiling mill with certain of the parts broken away or removed to better illustrate various features of the mill;

Figs. 3 and 4 may be arranged similarly to Figs. 1 and 2 and, when so arranged, illustrate generally in central vertical section the reversible hot strip coiling mill, shown in Figs. 1 and 2;

Fig. 5 shows in end elevation one of the coiling furnaces embodied in the reversing coiling mill;

Fig. 6 is a view taken substantially along the line 6-6 of Fig. 3 looking in the direction of the arrows;

Fig. '7 is a schematic diagram of the electrical network for the driving motors;

Fig. 8 is a schematic diagram of the electrical controlling network for the mill;

Fig. 9 shows diagrammatically the construction of certain of the switches diagrammatically shown in Fig. 8;

Fig. 10 is a schematic diagram of the electrical controlling system for the strip guides;

Fig. 11 is a schematic diagram of the electrical torque-controlling system for the coiler drum motors; and,

Fig. 12 is a section view taken substantially along the line I2I2 of Fig. 1 showing the guide actuating mechanism.

It will be appreciated from a complete understanding of the invention that, in a generic sense, the improvements thereof may be embodied in a wide variety of difierent rolling mill constructions. Therefore, the embodiment shown in the drawings is to be taken as illustrative and not as limiting the scope of the invention, which scope is to be limited only by the hereinafter appended claims.

Referring to the drawings by characters of reference, the numeral I designates generally a hot strip reversing rolling mill which may be located along a table of a fiat-type billet rolling mill having work rolls which receive a metal billet from a furnace. The flat rolling mill may be of any usual type in which the work is passed through the work rolls to reduce the thickness thereof to a suitable dimension for use in the mill I. After such treatment of the metal, the operator in one of the booths or operating pulpits of the mill I actuates suitable controls whereby the strip enters the mill I.

The mill I is brought into operation and the metal strip is fed through the work rolls I4 and backing rolls I5 of the mill I in alternate directions until the thickness thereof has been brought down to a coiling dimension. Suitable controls, to be hereinafter described, are then actuated to initiate coiling of the strip about one of the coiler drums I6 or I8 of the right and left coiling furnaces 20 or 22 respectively. The particular furnace 20 or 22 which is first used will depend upon whether the strip is first run through the mill I in a right-hand or left-hand direction. After the hot strip has been completely run through the work rolls I4, the coiler drum I6 or I8 upon which the strip is being rolled is stopped and the work is then passed through the Work rolls I4 in the opposite direction to be coiled upon the opposite one of the coiler drums I8 or I6. Thereafter, the strip is repeatedly run through the work rolls I4 in alternate directions and coiled upon the drums I6 and I8 alternately until the thickness of the strip has been reduced to the desired thickness. Subsequently, the strip is fed outwardly from the mill I to a suitable coiling station (not shown) where it is coiled into suitable form for delivery from the mill.

The reversing coiling mill I comprises generally a worktable 24 in which the right and left-hand coiling furnaces 20 and 22 respectively are located. Intermediate between the furnaces 20 and 22 are positioned the work rolls I4 for reducing the thickness of the metal strips fed along the worktable 24 from one of the coiling furnaces 20 and 22 to the other of the coiling furnaces 22 or 20. Any suitable mechanism for controlling the spacing between the work rolls I4 may be used and, since such mechanism is well known to the art, it is not deemed necessary to complicate this disclosure by a detailed showing thereof. The worktable 24 may include one or more rotating rollers 26 over which the metal strip being treated is passed and which rollers 26 may, if desired, be driven by one or more electrically operated motors 28 adjusted to rotate at the speeds of the stri portion supported thereby during rolling operations. If desired, they may be operated similarly to the operation of the motors LCM and RCM to be more fully described hereinafter.

A pair of substantially parallel, spaced guides 30 are arranged adjacent the right-hand side of the work rolls I4 and spaced one on either side of the central axis of the worktable 24. A second set of parallelly arranged, spaced guides 32 are similarly arranged on the table at the left side of the work rolls I4. These guides 30 and 32 are connected by suitable mechanism whereby, when one set of guides, for example, guides 30, are arranged in guiding position, the guides 32 are moved to a further apart position; and, conversely when the guides 32' are arranged in guiding position, the guides are spaced apart a greater distance.

Fig. 12 shows the construction of the adjusting mechanism for the guides 32 having guiding surfaces between which the strip being rolled is guided. A screw-threaded rod I32 is suitably journaled for rotation in bearings, not shown, and has threaded end portions I34 and L36 of opposite hand. Nuts I38 and I are threaded on the portions I34 and B6 respectively and are pivotally connected to lever arms I42 and 544 respectively and serve as fulcrum points therefor. The upper ends of the arms I42 and I44 are pivotally connected through link pins I48 to the guides 32. The lower ends of the arms I42 and [44 are pivotally connected through links I48 to diametrically opposite pins I of a rotatable member I52 journaled on a shaft I54 suitably held in supports I56. A crank arm I53 is arranged to be moved by a link I50 for rotating the member I52 between the position shown in which the guides 32 are in guiding position to a position in which the lower ends of the arms I42 and I44 are brought inward toward each other and the gudes 32 are moved to a retracted or non-guiding position. A similar construction of arms and links actuate the guides 38 and are controlled by a link I62. The reversible guideadjusting motor GAM is suitably held on a support, not shown, and is connected through suitable reduction gearing I64 for rotating a shaft I65 in opposite directions. The shaft IBS is journaled in suitable bearings I68 and has attached thereto for rotation thereby a pair of crank arms Ill) and I72 to which the links Hit and I62 are respectively pivotally attached. The crank arms I70 and I12 are positioned at 180 relative to each other so that as the link Itfl is moved toward the table 24 the link I52 will be moved outwardly therefrom. Such movement of link [53 will rotate the rotatable member I52 to the position shown in which the lower ends of the arms I42 and I44 are in their separated position and the guides 32 in their guiding position. Similarly, the outward. movement of the link I69 will draw the lower ends of the arms I42 and I44 toward each other and retract or separate the guides 32. The guides 39 are actuated similarly by the link I so that the guides 30 will be retracted when guides 32 are in guiding position and vice versa. Suitable switch means GSR and GSL limit the operation of the motor GAM so that the shaft I has only limited rotational movement of substantially 180 whereby the arms Ilil and I12 are either in the position shown or 180 therefrom.

As will be noted, a hand crank I'M is provided .on the rod I32 whereby it may be rotated to adjust the position of the fulcrum nuts I38 and M0 for adjusting the spacing between the guides 32. A similar crank I76 is provided for the corresponding rod for the guides 30 whereby their spacing may be controlled in a similar manner.

The coiling furnaces 2i and 22 are identical and therefore it is believed that a detailed description of one will suffice as a description for both. The furnace 28 comprises a refractorylined base 34 which is substantially rectangular in cross section and has a closed lower end wall 35 and an open top wall above which a cylindrical, refractory-lined hood 3t is located and which has had a segment of its cylindrical surface removed to provide an opening through its peripheral surface. The. hood 38 and base 34 are suitably heated whereby heat lost during; the rolling operations may be returned to the strip. The coiler drum. I6 is located within. and extends longitudinally of the hood 38'. This coil-er drum it comprises a hollow, cylindrical member 40 having diametrically opposite apertures 42: opens ing externally into the hollow interior oi the member 40. The apertures 42 have one side wall extending at an angle therethrough which is acute with respect to the tangent line of the drum at its intersection with. the outer periphery of the drum I6 whereby the leading end of the strip may easily pass therethrough. The inner periphery of the hollow member 40 has. a slight protruding portion 43 adjacent the edge of the slots or apertures 42 opposite to the angular side wall, whereby the leading end of the strip being rolled is prevented from passing outwardly through the apertures 42 subsequent to entry into the member 40 and which tends to coil the portion of the strip within the drum I5 should the drum fail to start and come up to speed as soon as the leading strip end enters the same.

The furnace 20 is carried on a suitable sup porting base 44, which base also has upwardly extending supports 45 for supporting guide rolls 48 and 50. As shown in Fig. 1, the guide rolls 48 and 50 comprise central shafts 52 upon which are mounted a plurality of spaced disks 54, the upper edge of the periphery whereof lies substantially in the plane of the work surface of the Worktable 24. Located intermediate the guide rollers 48 and 50 is a coiler roll 56 which is carried by a vertically reciprocal supporting member 58 operated by a fluid pressure-actuated motor 6% located adjacent the support 44 and movable by the fluid motor into a position in engagement with the outer periphery of the coiler drum Ni and into a lower position in which the peripheral surface of the coiler roll 56 is below the plane of the surface of the worktable 24. Suitably pivoted counterweights 6i aid the movement of the members 58 by the motors to.

A plurality of guide fingers 62 are carried by the supporting member 58 and are arranged to project between the disks 54 of the guide roll 48. These guide fingers 62 are arranged at such an angle relative to the plane of the worktable 24 that when the coiler roll 56 is engaged'with the coiler drum 16, they guide the end of the metal strip being fed into the furnace 2D upward from the plane of the table 24 and through one of the apertures 42 of the coiler drum I5 whereby the end of the metal strip is received within the hollow interior of the member 4!]. During the time that the end of the metal strip is initially being fed to the coiler drum it, this drum I G is held at rest in the position shown in Fig. 4 by suitable control mechanism to be hereinafter de scribed. After the leading end portion of the metal strip being rolled is received within the hollow interior of the member 40, the coiler drum i6 is then rotated whereby the remainder of the strip being fed to the furnace 2B is wound or coiled around the exterior of the member 40. After the member 40 or coiler drum It has made at least one complete revolution, the strip will be held to the drum it by itself and the fluid motor 6G is (is-energized, thereby moving the coiler roll 58 downwardly below the plane of the worktable 24,

The coiler roll 56 is held in this position until such time that the strip is either through the work rolls I4 or is about to go through them, at

which time the fluid motor 60 is again energized, bringing the coiler roll 56 into contact with the portion of the strip rolled about the coiler drum l6 whereby the strip is held tightly to the drum l6 and against unwinding. It is to be understood that the coiler drum [6 will be automatically stopped after the strip has passed completely through the work rolls I4. In this condition, as explained hereinbefore, the strip is ready to be passed in the reverse direction to the work rolls [4 and recoiled upon the coiler drum 18 cf the left-hand coiling furnace 22. Suitable electric motors LCM and RCM drive the guide rolls 48 and 50 and the coiler roll 56 of the left and right furnaces 22 and 20, respectively, through suitable gearing 66 and shafts 68, and 12.

Suitable mechanism to be hereinafter described controls operation of the motors LCM and RCM at the proper speed so that there is little, if any, difference in speed between the speed of the strip and the peripheral speed of the rolls 48, 5B and 55.

The coiler drums l6 and [8 are driven by motors RRM and LRM, respectively, through a suitable gearing 16 and shafts 18. The motors LRM and RRM, like the motors LCM and RCM, are controlled by mechanism to be hereinafter described, so that the coiler drums l6 and I8 are rotated at approximately the correct speed to wind the strip about their periphery at a speed such that the amount of metal being rolled on the drum is equivalent to the speed at which the metal strip is fed thereto.

It is believed that the remainder of the details of construction may best be described in connection with the description of operation of the rolling mill. Assuming that it is desired to condition the coiling mill for operation, the line switches LSI and LS2 are closed thereby energizing the lines LI and L2. The billet which has been removed from the furnaces and run through the initial work rolls where it has been reduced from the original approximate 4" thickness to substantially 40% of that thickness, or slightly less than 2 in thickness, enters one of the furnaces 20 or 22 depending upon whether the rough work rolls are at the right or left-hand side of the hot-strip reversing mill I. In this instance, it is assumed that the rough work rolls are arranged to the right of the right-hand coiler furnace 20 and the leading end of the strip enters through the furnace 20 to the work rolls l4 associated with the worktable 24.

The next operation is to pass the strip in flat condition back and forth through the work rolls I 4 until such time that the thickness thereof has been reduced to a thickness in which the strip may be easily coiled in the coiling furnaces 20 and 22. It will be assumed that the operation in the left booth or pulpit is controlling the rolling of the fiat sheet down to a thickness in which it may be coiled in the furnaces 20 or 22. If desired, the strip may be rolled down to coiling thickness in other work rolls separate and apart from the mill I.

The left operator moves his master switch LMS in a direction to close the contacts LMSl-l and 2 thereof. The strip will be engaging the right flag switch RF and holding it in a position to maintain the contacts I, 2 and 3 thereof closed. It is further assumed for this operation that the left and right trigger switches LT and RT are in their lower position maintaining their contacts I in open-circuit position and their contacts 2, 3, and 4 in closed-circuit position. Closure of the contacts LMS 1-! of the left master switch LMS energizes a circuit from the line Ll through the contacts LMSl-I, the contacts LT2, the energizing coil of the relay CL, the contacts CRlfl of the relay CR, and the contacts E2 of the emergency stop relay E, to the line L2. Closure of the contacts LMSl-2 is without effect since the switches LLM and RLM and the contacts RSLZ of the relay RSL are in open-circuit position.

Energization of the relay CL closes the contacts 2, 3, 4, 5, 6, 1, I0, II and I2 thereof, opens the contacts I, 8, Ba and 9 thereof and decreases the magnitude of the resistance FRI which is located in the circuit of the main generator field MGf. The effect of the opening of the contacts CL!) and CLBa will be described hereinafter.

The construction of the relays CL, CR, RSL and RSR is quite similar and somewhat unique. Generally, they comprise a movable element or rod having an armature 92 which is moved under the influence of a solenoid winding 94. The rod 90 is moved toward down or de-energized position by suitable means such as a spring 98 and toward up or energized position by the magnetic effect exerted on the armature 92 by the winding or coil 94. A dash pot 98 permits rapid movement of the rod 90 to deenergized position but provides a controlled gradual movement toward energized position. A contact closing element 100 is associated with each set of normally closed relay contacts and is in fixed position relative to the rod 90 so that upon initial movement of the rod 90 toward energized position the normally closed contacts are opened. A relatively movable contact-closing element I02 is associated with each set of normally open contacts. The elements I02 are loosely carried by the rod and are each engaged by one end of a spring 104 and urged thereby into engagement with abutments 106 on the rod 90. The abutments I06 are so spaced on the rod 90 relative to its de-energized position and the position of the set of normally open contacts with which it is associated, that it is held by the abutment out of circuit-closing contact therewith. The other ends of the springs I04 engage abutments I08 on the rod 90. Upon energization of the coil 94, the rod 90 moves upwardly and the elements I02 make an electrical circuit between the con tacts with which they are associated and, as the dash pot 98 permits further upward movement of the rod 90, the springs I04 compress and permit such further movement.

The relays CL-CR and RSL-RSR are arranged in pairs. The rods 90 of the relays each have a projecting finger I I0 which engages a pin or abutment I H. of a spur gear I I4 meshing with a rack H6. The fingers H0 or relays CL and CR project toward each other and are each engageable with the pin H2 of the single gear H4 associated therewith. Likewise, the fingers H0 or the relays RSL and RSR are each engageable with pin H2 of the single gear H4 associated therewith. As the rod 90 of relay CR or CL moves upward, the associated gear H4 is rotated moving the associated rack H6 upwardly causing a contact element H8 carried thereby to move along the resistance FRI to decrease the portion thereof included in circuit with winding MG A spring I20 acts to return the rack H6 associated with the relays CL or CR upon deenergization of the relays. It is to be understood that either relay acting alone can move the associated rack H6 upwardly so that energization of one controls the position of reduced resistance of FRI. If desired, the elements 100 could be constructed similarly to the elements 192 and the abutments thereof corresponding to "it. as well as the shown abutments 185, could be arranged to provide any sequence of opening and closing of the contacts associated with the relay. The relays ESL and RSR are similarly paired and control the effective value of the resistance PR2 for controlling the current flowing through the field MMf. In this instance, however, as the relay RSL or RSR moves upward, the value of the resistance FRZ included in the circuit of the field MM, is increased to progressively increase the speed of the main motor MM.

Opening of contacts CLI opens the dynamic braking circuit through the resistor DRI. Closure of contacts GL2 connects the armature circuits of the main generator MG and the main motor MM; the motor MM being connected for driving the rolls l4. Preferably the contacts CLI open just before the contacts CL2 close. Closure of contacts CL3 and L4 closes a circuit from the line Li through contacts GL4, the main generator field MG the contacts GL2 and armature resistor FBI to the line L2. The main motor field MM was energized upon closure of the switches LS! and LS2 since it is directly connected between the lines LI and L2 through the resistor FRZ. The main motor MM so connected will now rotate the rolls M in a direction to roll the strip in a direction from right to left. Closure of the contacts CL5 completes a circuit from the line Li through the contacts GL5, the resistor FR3 and the left and right generator compensating field windings LGcf and RG01; the purpose of which will be set forth hereinafter.

Closure of contacts GL6 and CL! closes the armature circuit of the guide adjusting motor GAM, whereby the right-hand guides 30 will be brought to guiding Width for the strip which is being rolled. The left-hand guides 32 at the same time will be moved apart out of guiding relationship to the sheet. Upon movement of the guides 30 into guiding position, the limit contacts GSL will open to de-energize the motor GAM.

Closure of the contacts CL) is with no effect. Closure of the contacts CLH energizes circuits from the line Li, through contacts CLl I, through the coil of the relay LSC', through the parallelly arranged switch LRLS and contacts 4 of the left trigger switch LT to the line L2, and through the coil of the relay RSC, the parallelly arranged switch RRLS and contacts 4 of the right trigger switch RT.

Opening of the contact GL9 prevents the closure of the circuit through the control coil of the relay CR and is merely an interlocking arrangement whereby the relay CR may not be operated when the relay CL is energized.

Subsequent to opening and closing of the contacts of the relay CL, the rod 90 thereof moves upward under control of its dash pct 98 compressing its associated spring H34 reducing the portion of the resistance FRI included in the circuit of the main generator field MG), whereby the strength of this field is increased and the potential output of the main generator MG is increased thereby increasing the speed of the main motor MM.

The energization of the CL relay, among other functions, therefore acts to energize the main motor M in a left-hand rolling direction to bring it up to a first or threading speed, and to 10 adjust the guides 30 and 32 for guiding the strip in its left-hand travel through the rolls l4. Hereinafter, these functions of the relay CL will be referred to as energizing the motor MM and adjusting the guides for left-hand rollmg.

Energization of the relay LSC opens the contacts I and 2 thereof and closes the contacts '3, 4 and 5 thereof. Opening of the contacts LSO! and LSC2 opens respectively the dynamic braking circuits for the motors LCM and LRM. Closing of the contacts LSC3 and LSC4, which preferably occurs slightly after opening of the contacts LSCI and LSCZ, connects the armatures of the motors LCM and LRM to the generator LG. Closure of the contacts LSC5 connects the main field LGmf of the generator LG across the armature circuit of the constantly excited pilot exciter PE, which is driven by the main motor MM and will, therefore, generate a potential which is proportional to the rotational speed of the main motor MM.

Energization of the relay RSC opens the contacts l and 2 thereof and closes the contacts 3, 4 and 5 thereof. Preferably, the opening of the contacts I and 2 thereof occurs slightly before the closure of the contacts 3, 4 and 5 thereof. Opening of the contacts R801 and RSC2 opens, respectively, the dynamic braking circuits of the motors RCM and RRM. Closure of the contacts R803 and RSC4 connects the armature circuits of the motors RCM and RRM, respectively, to the generator RG. Closure of the contacts RSC5 connects the main field RGmf of the generator RG to the output of the pilot exciter PE.

The relays LSC and RS0, therefore, act upon energization to connect the armatures and fields of the motors LCM-LEM and RCM--RRM to the generator LG and RG, respectively, and to de-energize the dynamic braking circuits of these motors, whereby they drive the coiler drums l6 and i8, guide rolls 48 and 5 0 and coiler rolls 56 in the proper direction determined by the relative polarization of the armatures and fields thereof. The constantly excited pilot exciter PE, it is noted, is directly rotated by the main motor MM and is driven in the same direction. Therefore, when the main motor MM is rotated in a direction to rotate the work rolls l4 for rolling in a lefthand direction, the potential generated by the exciter PE will be of one polarity and upon the reverse rotation of motor MM the potential will be of a reverse polarity. The main fields LGmf and RGmf of the left and right generators LG and RG will be supplied with a potential of a polarity which is dependent upon the direction of rotation of the main motor MM. Since the fields lcMf -LRMf and RCMf-RRM of the motors driven by the generators LG and RG, respectively, are of a fixed polarity as determined by the polarity of the line L! and L2, the motors LCM-LRM and RCM-RRM will rotate in directions as determined by the master motor MM. The field and armature polarities of the motors LCM, LRM, RCM and RRM are initially adjusted to provide for motor rotations so that the coiler drums l3 and IS, the coiler rolls 56 and rolls 48 and 50 are rotating in the proper directions for transfer of the strip from right to left or left to right as determined by the rotation of the main work rolls M. In the remainder of the description, therefore, the relays LSC and RSC' will be described merely as energizing the motors LCM-LEM and RCM-RRM of the left and right coiling stands or furnaces 22 and 20-, re-

1 1 spectively, for transfer of the strip being rolled.

It will now be seen that all of the motors MM, I

LCM, LRM, RCM and RRM are now rotating under control of the generators LG, MG and RG and the pilot exciter PE. The field and armature connections of the above-identified motors are all respectively connected so that they turn in the proper direction for moving the strip to be rolled in the left-hand direction through the work rolls M. The rolling of the strip through the rolls I4 may continue at this motor speed for a reason which, as will be apparent further in description of the operation, is known as threading speed or, if desired, the speed may be increased to rolling speed. If rolling speed is desired, the switch LLM is closed to complete a circuit from the line Ll through contacts LMS!-2, the switch LLM, contacts RFZ, the energizing coil of the relay RSL, contacts E4 to the line L2. Energization of the relay RSL closes the contacts I and 2 thereof and decreases the current flow through the main motor field MM Closure of the contacts RSL2 completes a holding or looking circuit for the relay ESL and subsequent opening of the switch LLM, therefore, does not interrupt the high speed rolling operation. Upon actuation of the relay RSL, the contacts I thereof close rapidly but, because of the dash pot control of the arm of the resistance FRZ, the decrease of fieldstrength of the motor MM will occur gradually so that the acceleration of the motor M will be gradual producing an effect similar to that produced upon actuation of the relays CL or CR. After the expiration of the predetermined time as determined by the dash pot 98 thereof, the full resistance of the resistor FRZ is included in the field circuit MM whereby the speed of the main motor MM is increased sufficiently to produce rolling speed of the strip. Preferably the abutment I06 controlling the element I02 associated with the contacts RSLZ is positioned to close at substantially the time the rod 90 of the relay RSL reaches its upper limit and upon de-energization of the relay to open almost immediately so that upon increase in speed the operator maintains the switch LLM depressed for the period of dash pot operation during which time the holding contacts RSL2 are closed.

This increase in speed of the main motor MJVI drives the pilot exciter PE at an increased rate, thereby increasing the excitation on the main field coils LGmf and RGmf of the generators LG and RG, respectively, and an increased potential will be generated thereby. An increase in th potential applied to the motors LCM, LRM, ROM and RRM will cause their speed to increase and the rolling operation will proceed at rolling speed, for example, 1000 feet per minute.

As the end of the strip being rolled approaches the rolls 14, the operator moves the switch LMS to neutral position. This opens contacts LMSl-2 which de-energizes the winding of the RSL relay opening the contacts I and 2 thereof. As stated above, the contacts RSL open almost immediately so that a subsequent reclosure of the switch LMS in left position for closing contacts LSMI-l and LMSl-2 will not re-energize the relay RSL but will provide merely operation at threading or low speed.

When the strip has moved through the work rolls I 4, the operator in the left pulpit moves master switch LMS to the neutral position opening the contacts LMSI-l and LMSI-2. Opening of the contacts LMSl-l de-energizes the coilof the relay CL which de-energizes and brakes the motor MM but which is without effect on the motor GAM; it having already been de-energized by opening of the limit contacts GSL. Opening of the contacts CL2, 3 and 4 disconnects the main motor, armature and field, MM and MGf, respectively, from the main generator MG. Closure of the contacts CLI energizes the dynamic braking circuit for the main motor MM through the dynamic braking resistor DRI. Opening of the contacts CL5 de-energizes the circuit from the line Ll through the generator field LGcf and RG0). Opening of the contacts GL6 and CH is without effect since the circuit therethrough has previously been de-energized by the guide switch GSL. Closure of the contacts CL9 is without effect since both master switches LMS and RMS are now in their neutral position and the right trigger switch RT is also in its down position, as shown. Closure of the contacts CLIU is also without effect since the left trigger switch LT is in its down position, as shown. Opening of the contacts CL-ll de-energizes the relays LSC and RSC; the contacts CRH being in open circuit position.

De-energization of the relays LSC and RS0 de-energizes and brakes the motors LCM, LRM, RCM and RRM. Opening of the contacts 3, 4 and 5 of the relays LSC and RS0 disconnects the armature circuits of the motors LCM and LRM and the armature circuits of the motors RCM and RRM, respectively, from the generators LG and RG, respectively. Closure of the contacts I and 2 of the relays LSC and RSC closes the dynamic braking circuits through the resistors DR2, DR3, DR4 and DR5, respectively, whereby the motors LCM, LRM, RCM and RRM are brought to rest.

It is now assumed that the strip is still of a thickness which is too great to be coiled in the coiling furnace 22 and that another pass of the strip is to be made through the work rolls l4 without coiling. The movement of the strip to the right may be controlled by the operator in either of the left or right pulpits. For convenience, it will be assumed that the operator in the left pulpit is still controlling the rolling operation. The left master switch LMS is moved in a direction to close the contacts LMSrl and LMSrZ. Closure of the contacts LMSrl closes a circuit from the line Ll, through the contacts LMSrl, through the contacts I of the now closed. left flag switch LF, through the now closed contacts CL9, through the energizing coil of the relay CR, through the now closed contacts El of the emergency switch E to the line L2. Closure of the contacts LMSr2 is without effect since the switches RRMS and LRMS are presently in open circuit position and the contacts RSR3 are also in open circuit condition.

Energization of the relay CR closes the contacts 2, 3, 4, 5, 6, l, 9, H and I2 thereof and opens the contacts I, 8, 8a and [0 thereof. The effect of the opening of contacts CR8 and CRBa. will be described hereinafter. Preferably the contacts CRI are opened just a little ahead of closure of the contacts CR2. Opening of the contacts CRI de-energizes the dynamic braking circuit of the main motor MM through resistor DRI and closure of th contacts CR2 connects the armature circuit of the main motor M to the output of the main generator MG. Closure of the contacts CR3 and CR4 connects the main generator field MG) between the lines LI and L2, through the resistor FRI. The arm or finger I [0 under control of the dash pot 98 will move upwardly to gradually cut out the resistance in this circuit due to the resistor FRI thereby bringing the main motor MM. up to speed. Closure of the contacts CR5 completes an energizing circuit for the generator compensating field LGcf, through the resistor FR3. Closure of the contacts CR6 and CR7 completes a circuit through the gage adjusting motor GAM whereby the guides 32 will be brought together into proper guiding position and the guides 30 will be moved apart. A guide limit switch GSR. will open the circuit of the guide adjusting motor GAM upon bringing of the guides 32 to their proper guiding position.

Energization of the relay CR, therefore, performs for a part of its function the energization of the motors MM and GAM. It will be noted that the polarity of the potential supplied by the .generator is the opposite to that supplied upon the energization of the relay CL since the potential across the generator field MG) is reversed to that due to energization of the CL relay. Since the potential supplied to the motor field MMI is of constant polarty, the reversal of the potential supplied to the armature of the motor MM will cause the .main motor to rotate in a direction opposite to that due to energization of the relay CL, whereby the strip will be rolled from left to right.

Closure of the contacts CR9 is without effect since the contacts I of the right trigger switch RT are now in open-circuit position. Opening of the contacts CRIB is also Without effect except to prevent undesired energization of the relay CL. Closure of the contacts CRH completes a circuit from the line Ll through the contacts CRlI, through the energizing coil for the relays LSC and RS0. The remainder of the circuit from the coil of the relay LSC is completed through the now closed contacts 4 of the left trigger switch LT to the line L2; while the remainder of the circuit for the energizing coil of the relay RSC is completed through the now closed contacts i of the right trigger switch RT to the line L2.

Energization of the relays LSC and RS energizes, respectively, the motors LCMLRM and RCM-RRM as described above. A reversal in direction of the rotation of the main motor MM and, consequently, the pilot exciter PE. which is driven thereby, since the field of the pilot exciter is maintained energized at one polarity, will result in a reversal in potential of the output thereof. Therefore, closure of the contacts LSC and RSCE will cause an excitation of the main field LGmf and RGmf of the generators LG and RG, respec tively, opposite to that which occurred when the relays LSC and RSC were actuated by the relay CL. Since the direction of rotation of the generators LG and RG is maintained the same, the potential output of the generators LG and RG will be of opposite polarity to that when the main motor MM was rotating in a direction to move the Work strip from right to left. The main fields of the motors LCM, LRM, RCM and RRM are energized with a constant polarity potential by the lines LI and L2 and, therefore, the direction of rotation of the motors LCM, LRM, ROM and RRM will be opposite to that which occurred when the strip was being rolled through the work rolls E4 in a direction from right to left or in a direction for moving the strip from left to right. High speed roll-ing is accomplished by closing one of the switches LRMS or RRMS with the same effect on the main motor as occurred above when 14 the strip was moving to the left and switch LLM was closed.

After the strip has moved in a right-hand direction through the work rolls M, the operator again moves his master switch LMS to the neutral position opening the contacts LMSrI and LMSTZ thereof to de-energize the relay RSR and then recloses to continue at threading speed. To stop the rolling, the switch LMS is again moved to neutral position to open the contacts LMSM and LMSr2. Opening of the contacts LMSrl deenergizes the control relay CR since the contacts I of the right trigger switch RT and the contacts RMSTI and the contacts RSR2 are all in open condition. Opening of the contacts LMSTZ is without effect since the relay RSR. is already deenergized.

De-energization of the relay CR acts to close the dynamic braking contacts I thereof and open the potential supplying contacts 2, 3, it and 5 thereof for dynamically braking the main motor MM and de-energizing the circuits for the main generator field MG) and the compensating fields LGcf and RG0 of the generators LG and RG. Since the circuit for the motor GAM was previously de-energized by the limit switch GSR, the opening of the contacts CR6 and CRT is without effect.

Opening of the contacts CR9 is without effect. Closure of contacts CR'IO is without effect. Opening of contacts CRH, however, de-energizes the energizing circuits for the relays LSC and BBC to connect the dynamic braking circuits of the motors LCM, LRM, RCM and REM and to disconnect these motors from their respective generators RG and LG. The strip is manually rolled back and forth substantially as hereinbefore described under control of the operator in either the left or right pulpit until such time that the thickness thereof has been reduced sufficiently so that it will coil readily in the coiling furnaces 20 and 22.

Assuming that the strip has reached this thickness and it is located in a position in which it extends through the right-hand furnace 2B and will be rolled through the work rolls M in a lefthand direction under control of the operator in the left pulpit, the operator raises the left trigger switch LT thereby closing the contacts I, 5 and 6 thereof and opening the contacts '2, 3 and 4 thereof. Closure of the contacts LTI prepares a circuit through the contacts CLIO which are now open. Closure of contacts LT5 prepares a circuit through the left flag switch LP, the contacts LF3 thereof new being open because the strip is on the right-hand side of the work rolls M and not in a position to move this switch to its actuated position. Closure of the contacts LTt energizes a circuit from the line Ll through the energizing winding of the fluid supply valve VL, through the contacts LT6 and the normally closed contacts TL2 and TRZ to the line L2. This last-described circuit causes fluid to be admitted to the hydraulic cylinders 60 to raise the coiler roll 58 of the furnace 22 into engagement with the peripheral surface of the coiler drum [8. Opening of the contacts LT2 is without effect. Opening of the contacts LT3 opens the shunt circuit around the contacts RFZ and the contacts RSL2; switches LLM and RLM now being in open-circuit position. Opening of the contacts LT4 opens the shunt circuit around the contacts TL! and switch LRLS. The change in circuit conditions with the exception of the actuation of the value VL is preparatory only.

The operator now moves the left master switch LMS to close the contacts LMSI-I and LMSI-Z. Closure of the contacts LMSI-2 is without effect, while closure of the contacts LMSI-I completes a circuit from the line LI, through the contacts LMSI-I, contacts RFI, the energizing coil of the relay CL, contacts CRIIJ and E2 to the line L2. Energization of the relay CL starts the main motor MM and pilot exciter PE and adjusts the uides 30 and 32 as described above in connection with flat rolling.

Closure of the contacts CLIIl closes a circuit from the line LI, through the contacts LTI, the contacts CLIIl, the contacts RFI-I, CRIB, E2, to the line L2 by-passing the contacts LMSI-I. The energization of relay CL and, consequently, the motor MM is now under control of the right flag switch RF. Closure of the contacts CLII energizes the energizing windings of the relays LSC and R80 and, as hereinbefore described, this starts the motors LCM, LRM, ROM and RRM in the correct rotational directions. The lefthand motor LRM will rotate the coiler drum I8 until one of the apertures 42 thereof is positioned substantially as shown in the drawing (see Fig. 3) so that when the strip is fed into the furnace 22, it will go through this aperture and into the interior of the hollow cylindrical member 40 of the drum I8. When the drum I8 has reached this position, the limit switch LRLS thereof will open. Since contacts LT4 and TLI are open, the relay LSC will be de-energized and brake the motors LRM and LCM, as above described. The limit switch LRLS is selective as to direction in its operation and opens only upon clockwise rotation of the drum I8.

The strip is now proceeding from right to left through the Work rolls I4. When the leading end thereof engages the left flag switch LF, it will close the contacts I, 2 and 3 thereof. Closure of the contacts I and 2 has no efiect but closure of contacts LF3 completes a circuit from the line LI, through the contacts LT5, LF3, CLI2, through the energizing coil of the relay TL to the line L2. Energization of the relay TL, after a predetermined time interval which is suiiicient for the end of the strip to enter the aperture 42 of the drum I8, closes its contacts I and opens its contacts 2. Closure of the contacts TLI completes a by-pass circuit around the switch LSLR and completes a circuit from the line LI through the contacts CLI I, the energizing coil of the relay LSC and through the contacts TLI to the line L2. Energization of the relay LSC will act immediately to start the motors LCM and LRM to coil the strip.

Opening of the contacts 'IL2 de-energizes the energizing circuit for the valve VL and which valve, after a predetermined time interval determined by the discharge of the condenser CI connected in shunt with the coil of valve VL, will close and allow the fluid to escape from the ram 60 and the left coiler roll 56 to move out of the path of the strip. The timing of the discharge of the condenser CI is adjusted to close the valve VL after the coiler drum I8 has made just over one complete revolution so that the strip has locked itself securely to the drum I8.

The strip is now rolling through the work rollers I4 and into the furnace 22 at a relatively slow or threading speed, for example, 400 feet per minute. If the work was rolled at this speed, the furnace would be uneconomical in operation since the usual length of a strip of rolling thickness is several hundred feet. Therefore, after 16 the drum I8 has been threaded or has had the end of the strip attached thereto, it is usually desirable to operate the remainder of this rolling operation at a much higher speed.

To speed up the mill to rolling speed, the operator closes the switch LLM which energizes the relay RSL to speed up the motors MM, LCM. LRM, ROM and RRM as described in connection with fiat rolling. With the mill I running at rolling speed and under coiling conditions, the right trigger switch RT is moved to its up position closing contacts I, 5 and 6 thereof and opening contacts 2, 3 and 4 thereof. The effect is preparatory only.

Preferably, the operator controlling the rolling watches the end of the strip being rolled and when it is approaching the furnace 20, the left master switch LMS is moved into neutral position opening the contacts LMS I-I and LSMI-2 thereof placing the motors at threading speed and under control of the right flag switch RF. Opening of the contacts LMSI-Z de-energizes a circuit through the energizing coil of the relay RSL whereby the contacts I and 2 thereof are opened. In this instance unlike the flat rolling, opening of the contacts RSLI is without immediate effect since the contacts RFI of the right flag switch are now closed in by-pass arrangement around the contacts RSLI but does put the relay CL under control of the right flag switch RF. Opening of the contacts RSL3 de-energizes an obvious holding circuit for the coil of the relay RSL. Deenergization of the relay also causes the resistance of R2 to increase the current flowing in the field circuit MM of the main motor MM to increase the field excitation of the main motor MM, decreasing its speed and also the speed of the pilot exciter and, consequently, that of the motors LCM, LRM, ROM and RRM to the initial or threading speed of the mill I which proceeds with the master switches LMS and EMS in neutral position under control of the right flag switch RF.

As the end of the strip being rolled passes the right flag switch RF, this switch moves to its open condition opening its contacts I, 2 and 3. Opening of the contacts 2 thereof is without effect. Opening of contacts RFI de-energizes the energizing coil of the relay CL braking the main motor MM and opening control contacts II], II and E2 thereof and closing the control contacts 9 thereof. Closure of the contacts CL9 is without effect since it is merely a safety switch to prevent operation of the relay CR. when the relay CL is operated. Opening of the contacts CLII ole-energizes the relays LSC and RSC to brake the motors LCM, LRM, ROM and RRM. Opening of the contacts CLI2 de-energizes the relay TL closing the contacts TLZ which, if the trigger switches LT and RT are in their up position with the contacts 5 thereof closed, will energize the valves VL and VR through obvious circuits to move the coiler roll 56 into engagement with the coiler drum I6 and the strip wound about the coiler drum I8. It is realized that there will be a certain amount of inertia in the coiler drum I8, which by this time will have substantially all of the steel strip spirally wound therearound, and preferably the operation of the switches and the effect of the dynamic braking circuit itself is such that the coiler drum I8 will come to rest with the end of the strip spaced toward the work rolls I4 from the left flag switch LF, so that this switch will be maintained in a position to keep 17 the contacts LP! and LFZ in closed-circuit position.

If, however, the operator .does not move the master switch LMS to the neutral position above described, no great damage will result other than perhaps the .end of the strip will roll too far along the table and may move beyond the left flag switch LF. Under these conditions, the left master switch LMS will be in a position in which the contacts LMSl-l and LMSl-2 are closed. As the end of the strip passes the right flag switch, the contacts 2 and '3 thereof .open. Opening of the contacts RFl has no effect since under these conditions the contacts RSLl will be closed. Opening of the contacts RFZ de-energizes a circuit through the contacts RS142 which ole-energizes the energizing coil of the relay RSL. Opening of the contacts RES has no eflfect since the contacts CRlZ are open. De-energization of the relay RSL acts to increase the current flow through the main motor field MM due to the reduction of the resistance FRZ.

The contacts RSL l and v2 open upon .de-energization of relay R-SL. Opening of the contacts RSL] opens the circuit through the energizing winding of the relay CL since contacts RF! and LTZ are now open. Opening of the contacts RSL'Z is of no efiect since RSL already has been de-energized. De-energization of the relay CL acts as hereinbefore stated to brake the main motor MM and energize the valves VL and VR as above described. If the strip moves too far to the left and passes the left flag switch LP, the manual inching control MIR may be actuated I to close the relay OR to initiate operation of the main motor MM and? to energize upon closure of the contacts CLl l to energize the relay LSC to initiate operation of the motors LCM and LRM to bring the strip past the left flag switch LP. The strip now being substantially coiled around the coiler drum i8 with its end extending beyond the flag switch LF toward the work rolls it, the operator moves the left master switch L'Ms into a position which closes the contacts LMSrl and LMSTZ. Closure of the contacts LMSTZ is without efiect since switches LRMS and RRMS are open and also contacts BSRS are open. Clossure of .contacts LMST! completes a circuit from the line Ll through the contacts LMSTI, LFE, GL9, and the energizing coil of the relay CR, through the contacts E1 to the line L2. Energ-isation of the relay CR initiates the operation of the main motor MM and the setting of the guides for guiding the strip in left to right movement through the rolls i l. Energization of the relay CL also energizes the coils of the relays LSC and RS for operation of the motors LCM, LEM, ROM and RRM, as hereinbefore described. In this case, however, as soon as the motor REM has rotated the coiler drum it so that one of its apertures l2 thereof is substantially in the position shown in Fig. 4 for receiving the end of the strip,

the limit switch RR-LS thereof will open for deenergizing the relay RSC, whereby the motors ROM and RRM will be disconnected from the generator RG and their dynamic braking circuits will he applied. Limit switch RRLS like limit switch LRLS is directional in its operation; the switch RRLS opening only when drum It is rotating counterclockwise.

The motors LCM. and LRMwill be rotating and the strip will be fed through the work rollers from left to right toward the furnace 2:3. When the leading edge of the strip engages the right flag switch RF, the contacts I, 2 and 5% thereof will close. Closure of contacts RF] and RFZ is without .efiect, while closure of the contacts RF3 completes a circuit from the line Ll, through contacts R'I5, RES, CR IZ, the coil of the relay TR, to the line L2. Energization-of the relay 3BR causes its contacts i to close and its cont-acts 2 to open. Closureof the contacts TR! completes an energizing circuit from the line Li, through the contacts CR1! l, the coil of the relay RSC, contacts TRI .to the line L2 at the expiration of a predetermined time interval because of the dash pot associated therewith, to initiate operation of the relays LSC and RS0 subsequent to entering of the strip end into the drum [6. Opening of the contacts TRZ acts to de-energize the valves VL and VR. The condensers VLC and VRC are charged upon energization of the coils of the valves VL and and upon opening of the energizing circuits of these valves discharge through the respective coils to maintain the coils energized for a short time period subsequent to operation of the motors ROM and RRM so that the right and left coiler rolls 56 will not be withdrawn downwardly until the drum 16 has made one complete revolution.

Th strip is now being fed from left to right through the mill I at threading speed. To increase this speed to rolling speed, the operator closes the switch LRMS completing a circuit from the line L l, through the contact LMST-E, switch LRMS, contacts LFZ, coil of the relay RSR, contacts E3, to the line L2. 'Energization of therelay RSR causes the contacts l and 2 thereof to be closed and the resistance "PR2 gradually to be placed in the field circuit MM), thereby weakening the field of the motor MM and increasing its speed. Closure of the contacts RSRI and RSR2 has no effect other than to provide holding circuits.

The operator watches the number of turns of the steel strip remaining upon the coiler drum l8 and when this is reduced to one or two turns, he moves his left master switch LMS to the neutral position opening the contacts LMSH and LMsril. Opening of the contacts LMSTI is without effect since it is 'by-passed by the closed contacts RT! and CR9. Opening of the contacts LMS1'2 opens the energizing circuit for the relay 'RSR which immediately opens, opening the contacts l and 2 thereof and causing the resistance FRZ to be moved from the field circuit MM to reduce the speed of rolling to threading speed. When the end of the strip has passed by the left flag switch LP, the contacts i, 2 and 3 thereof will open. Opening of the contacts Ll?! de-energizes the relay CR to brake the motor MM and de-energize the relays LSC and RS0 for braking the motors LCM, LEM, ROM and RRM. Opening of the contacts LE3 ole-energizes the winding of the relay TL closin the contacts TLZ for energizing the valves VL and VB and the condensers VLC and VRC. Further reduction of the thickness of the strip and alternate winding and unwinding of the strip between the two coiler Y drums it and i8 continues in the manner described until such time as the thickness of the strip has been reduced to the desired dimension. After the strip is reduced to the desired dimension, it will be wound about one of the drums 16 or 53. Assuming that it is wound on the coiler N6, the left and right trigger switches are returned to the position shown in' Fig. 8, the work rolls M are spaced apart by a suitable means well known insthe art and, therefore, not shown or further described in this application, and the left master switch LMS is moved so that the contacts LMSI-I and LMS I'/! are closed. The strip now runs down along the table 24 through the now spaced apart work rolls I4 through the furnace 22 and along the worktable where it is coiled by suitable mechanism well known in the art and not further described, after which it is removed for further heat treating or delivery to the customer.

While the description of the operation has been specific with respect to the circuit control afforded by the left master switch LMS, it will be obvious that the right master switch EMS is connected in parallel relationship with the left master switch and that operators in either of the left or r ght pulpits may take control of the work. A duplicate set of left and right trigger switches may be provided; however, in usual installations one set is sufiicient; the operator having this set initially starting the coiling operation. Th switches RRMS and RLM are switches appearing in the right pulpit and correspond to the switches LLM and LRMS in the left pulpit. Switches MIL and MIR are, respectively, inching controls for moving the strip along the table manually without resort to any automatic control system for placing the motors in automatic operation.

It will be noted from the above description of operation that preferably the relays ESL and RSR act to promptly close their contacts I but the closure of their contacts 2 is delayed until substantially all of the resistance FRZ has been put into the energizing circuit for the main motor field MM In increasing the speed of the motor MM, it is necessary therefore for the operator to keep the switches LRMS, RRMS, LLM or RLM manually closed until the expiration of the time interval necessary to close the holding contacts 2 of the relay RSL or RSR. Such contacts 2 could be adjusted to close promptly and a momentary closure of the switches LRMS, RRMS, LLM or RLM would be sufficient. In this event, however, it would be necessary for the operator to maintain the master switch LMS or EMS in neutral position a suificient time to permit opening of the contacts 2 of relay RSL or RSR. The contacts I of the relays ESL and RSR, should remain closed to maintain the relay CL or CR energized until such time as the resistance PR2 has been reduced to minimum value for low speed motor field operation.

The relay E is operated by closure of switch ES which energizes its control winding through an obvious circuit for emergency stopping of the rolling operation. Upon such energization, the relays CR, CL, ESL and RSR are immediately de-energized for braking the motors MM, LCM, LRM, ROM and RRM,

Compensating field windings LGcf and RGcf have been provided for the generators LG and RG, respectively, and are under control of the contacts GL5 and CR5. Their field windings are energized with a fixed polarity potential between the lines LI and. L2. It will be obvious therefore that with one polarity of the left and right generator field winding LGmf and RGmj th compensating field windings LGc and RGcf aid and oppose and with the opposite polarity of the left and right generator field windings oppose and aid.

With the strip for example coiled on the left coiler drum I 8 and under conditions for rolling to the right through the rolls I4 and with the rolls I4 set to provide reduction in strip thickness, of for example 40%, the rolls operated by LCM must run slower than the rolls operated by RCM because the same volume of strip must be taken from the rolls I4 during any interval of time as is fed to the rolls I4. Also, the coiler drum I8, due to the fact that the strip being fed therefrom is wound spirally thereon, must run at a progressively increasing speed if the strip is fed therefrom at a constant number of feet per minute, because of the constantly reducing diameter of the strip on the drum I8. Likewise, the speed of the drum I6 upon which the strip is being spirally wound must be continually decreased because of the increasing diameter of the spiral.

For purposes of explanation, assume a threading speed of 400 feet per minute of strip being fed from the work rolls I4 and a 40% reduction in strip thickness as it passes through the rolls I4. Since there is substantially no increase in strip width upon passing through the rolls I4, there is substantially a 40% increase in strip length which will require faster rotation of the motors ROM and RRM in the ratio of 1 to 1.66 neglecting for the instant the changing diameter of the coiler roll. In order to simplify this discussion, speeds of the various drums and rolls will be expressed in feet per minute of the periphery thereof, the periphery of the coiler drums It and I8 being assumed not to be the actual periphery thereof the effective peripheral dimension at which the strip is being wound and which varies according to the amount of strip on the coiler drums. Further it is assumed that the ratio of coiler drum periphery to the periphery of the last turn of strip thereon at the end of the rolling operation is one to two. In some instances when convenient, the speeds of the various motors will be discussed and, when motor speeds are referred to, the speeds discussed will be the peripheral speeds at which the drums or rolls connected thereto are driven. For example, a speed of motor MM of 400 is the same as a speed of the rolls I4 of 400.

Now, therefore, under the assumed conditions, the various speeds at the start will be as follows: coiler drum I8, left coiler roll 56 and left rolls 48 and 50, 240; work rolls I4, 400; right rolls 48 and 58 and rightcoiler roll 56, 400; and coiler drum I6, 400. The speeds of the rolls will remain constant for the operation but those of the drums I8 and It will change from 120 to 240 and from 400 to 200 respectively. When the strip is rolled in the opposite direction, the work rolls I4 remain at 400 but the drum I8 and left rolls 48 and 50 operate at the same speeds which the right rolls 48 and 58 operated at when rolling from left to right while the right rolls 48 and 5E! operate at the same speeds as did the left rolls 48 and 58 in the left to right rolling. The normal speed of the drums I8 and I8 as determined by the potential of the right and left generators RG and LG due to excitation thereof by the fields RGmf and LGmf, respectively, with normal excitation on the motor fields RRMf and LRMJ is 260. Therefore, if the compensating fields of the generators RGCf and LGcj are of a value to provide a speed and are polarized to aid and oppose respectively the fields RGmf and LGmf, the drums I6 and I8 will rotate at speeds of 120 and 400 respectively, which speeds are those desired for left to right rolling. Therefore, upon initial rolling, the motors RRM and LRM operate at approximate correct speed.

The motors RCM and LCM are driven by the right and left generators RG and LG respectively 21 in parallel with the motors RRM and LRM respectively. Assuming a normal starting speed of the motor LRM of 240 and necessarily with the same compensating effect for the winding LGcf the normal speed with an uncompensated left generator LG would be 520. This figure is arrived at by the following method: normal speed of motor LRM (260) is to normal speed of motor LCM (unknown) as the compensated speed of motor LEM (120) is to the compensated speed of motor LCM (24 The result of this equation provides the 520 figure. The difference between 520 and 240 is 289 which is the compensating effect of the winding LGcf. Since the winding RG01 aids the winding RG f, the motor RCM will have a normal speed of 520 plus 280 or 8.90 which is greatly in excess of the desired speed. Resistors FR l controlled by the relays CR and CL respectively, are, therefore, provided in the field circuit for the field windings LCMf and RCMf. By arranging the resistor PR4 in the circuits for fields LCM) and RCMf and placing a shunt circuit around the resistors controlled by normally closed contacts CR8 and GL8 of the relays CR and CL and properly proportioning the value of the resistor PR4, the speeds of the motors LCM and RCM may be made 240 and 400 and 400 and 240, respectively, depending upon the rolling direction.

Since as above stated, the change in potential generated by the generator LG- due to the effect of the winding LGcf is too great, the normal speed of the motor LCM is lowered an amount such that, with the field LCM) thereof energized in accordance with the potential of the generator LG, the low left to right rolling speed of the motor LCM is reduced below the desired speed and the high or right to left rolling speed is reduced to the desired speed. If now the resistance FRA is placed in series circuit with the winding LCMf, the strength thereof for any given potential of the generator LG will be decreased causing an increase in speed of the motor LCM. The value of the resistor FRd is, therefore, so chosen that when placed in series circuit with the field LCM, the strength of this field is reduced suificiently to bring speed thereof up to the desired low speed of 240. Since the contacts CR8 are open for left to right rolling, the resistor FR will be in series circuit with the field LCMJ and the motor LCM will be rotating at desired speed. When the rolling is being done in a right to left direction, the contacts CR3 are closed and the resistor PR4 effectively lay-passed, whereby the energization of the field LCM! is as if no resistor F34 were added. Likewise, the resistor FR l controlled by contacts GL8 relay CL is associated with the motor RCM in the same manner.

Since the speed of rotation of the pilot exciter PE varies in accordance with the speed of the main motor MM, the potential generated thereby will also vary. Since the ratio between the excitation of the fields LGcf and RGcf with respect to the fields LGmf and RG-mf, respectively, must remain constant, the potential supplied to the fields LGcf and RG0) must vary in proportion to the potential of the exciter PE. Since the polarity of the fields LGcy and RGcf must remain fixed, they cannot be easily supplied by the exciter PE without complicated switching. A resister FEE has, therefore, been provided which is adjustable along with the resistor FRZ to provide for an increasing excitation of the fields LGcf and RGcf (decrease in value of resistance of FR3) with an increasing speed, of the .mot

(increase in value of resistance F32) whereby the relative strengths of the fields .LGmf RzGmf and LGcfRGcf are maintained constant.

larly the terminals bl, b2, b3, cl, c2, 03, d1, 012

and .123 are to be connected to correspondingly identified terminals of the regulators TR'Z, TR3

I and TRG.

The tension regulators TR] TRZ, TR3 and TR l may be of any suitable type in which the motors controlled: thereby are automatically controlled to transmitconstant power to the load or to regenerate constant power from the load. One such arrangement is schematically shown in Fig. 12. The regulators TBA, TEE, TR3 and TR i are identical. The regulator TRI, as shown in Fig. 12, comprises a pair of spaced series connected field coils 280 ,and'2gfi2 arranged to be connected in series with the'armature circuit of the motor LCM and a rotatable coil 2% arranged between the'coilsZM and 202 and connected in series circuit with a high value variable resistor R! and across the armature terminals of motor LCM. The coil 284 will be rotated against the force of a suitable return spring, not shown, in proportion to the product of the forces exerted by the current flowing in the coils 2lli322 and the coil 205. The current in coils 2M) and 262 is proportional to the current through the armature of motor LCM while the current in coil 28% is proportional to the potential across the armature of motor LCM. Therefore, the coil 2% is rotated in accordance with the product of the motor volts and amperes and will. assume a given position for a given power of the motor irrespective of the relative magnitudesof current and voltage.

The coil ZMcarries an arm 2% having a contact which cooperates with a resistance element 298 wereby the energization of the field LCM may beregulated. Under motoring conditions of the motor LCM, the contacts CR8 will be closed and the resistor FR i will be shunted out so that it has no effect on the energization of the coil LCM). The resistance element 2&8 is positioned relative to the arm 2% so that when the desired power is being supplied to the motor LCM, the 'value'of the'resistance of the element 208 included in the circuit of the field LCM) is that required for this operation of the motors at the desired power and the circuits are in balance.

-As the load on the motor increases, the arm 2% will be movedin a clockwise direction to decrease the value of the resistance in circuit with field LCM The resistance element 268 is positioned relative to the arm 2% so that when the motor LCM is operating for right to left rolling of the stripat just over the desired speed of 4:00 with nopower delivered to or absorbed from the strip or in other Words exerting no motoring of regenerative effect, the arm 2% is located substantially midway of the element Zilii, as shown in Fig. 11. The biason the arm 296 is such that the power so required to drive the motor LCM as described and reflected by the coil 2% will hold the arm 52,96. in this substantially central position of the .elernent:2il8 andthe value of the resistance of element-11min the. circuit of the field. ,LCMf is that required to permit the correct degree of energization of this field. Since the motor LCM cannot operate under these conditions because the strip speed is only 400, the motor will run at 400 and deliver power to the strip. This increase in delivered power of the motor LCM is reflected by an increase in power supplied thereto by the generator LG and by a movement of the arm 206 in a clockwise direction under influence of the rotatable coil 204, whereby the value of the resistance 288 included in the circuit of field LCM) is decreased to increase the excitation of the field LCMf. The change in resistance so afiorded is just sufiicient to decrease the normal no-load motor speed an amount such that the motor LCM will operate at the 400 speed and deliver the desired predetermined amount of power to the strip.

If now for some reason or other the power absorbed by the motor LCM from the generator LG tends to increase, the arm 286 under the influence of the coil 284 will move clockwise thereby decreasing the value of the resistance of the element 268 in the circuit of field LCM) increasing the field strength thereof and tending to make the motor operate at a lower speed but with the same power output. Since motor LCM is designed to operate at a constant speed because the strip is passing over the rollers driven thereby at fixed speed, the use of the regulator TR! is precautionary only and should seldom, except in cases of disruption of normal operation, be called into play.

The regulator PR3, however, has an important function. The normal speed of the motor LRM which drives the drum i8 is adjusted by its regulator TRS, with the contacts CLfia open and thereby rendering the resistor FRE eifective, to a speed just above the initial desired operating speed. With the strip being wound directly on its peripheral surface, it must operate at the 400 speed and the regulator TR3 will adjust the strength of its field LRM so that when operating at the 400 speed it will deliver the desired power to the strip, as described in connection with regulator TRi and motor LCM. As the strip is wound about the drum the effective drum diameter at the point of winding is increased and the speed of the drum i8 must be reduced since the strip will tend to be wound on the drum it faster than it is delivered by the rolls it. If

the motor speed were not reduced, the strip would be torn apart. However, as the efiective winding diameter of drum it increases and the strip tends to wind on the drum iii faster than it is delivered by the rolls E4, the power required to drive the motor LRM will increase. This increase in power is immediately reflected by the coil 204 which rotates the arm 2% clockwise to decrease the value of the resistance of element 208 in the circuit of the field LRM increasing the strength of the field LRM and decreasing the speed of the motor LRM. f-he relationship of the movement of the arm 296 by the coil 204 relative to the element 208 provides for an increased excitation of the field LRMj in correct proportion to reduce the speed of the motor LRM whereby constant power is delivered thereby to the drum i8. Therefore, since the power delivered by the motors LCM and LRM is held constant and the strip speed is constant, the tension of the strip leaving the rolls i l will be constant.

Referring to the motor LRM and assuming the strip is moving from left to right, the motor LRM will act to apply a resisting pull or tension substantially fully wound thereon.

on the strip as it enters the rolls I 4 and they, therefore, will be regenerating power into the generator LG which will be of a constant magnitude since the tension of, and speed of, movement of the strip into the rolls I4 is to be held constant. Under such conditions, the relay contacts CL8a will be closed due to the de-energization of relay CL and the value of the resistor FEE associated with the fields LRM will be subtracted from the resistance of the portion of the element 298 in circuit with the field LRMf to increase the strength thereof.

The value of the resistor PR5 is chosen so that when its value is subtracted from the value of the resistance of the element 288 and the arm 2% is at the substantially midway setting, the excitation of the field LRM is such that at noload the motor LRM will operate at a speed slightly less than which, as stated hereinbefore, is the initial desired speed for the drum [8 when unwinding. It should be here noted that as far as the operation of the regulator is concerned this is equivalent to the 400 speed because the reduction from 400 to 120 is accomplished by the efiect of the field LGcf. The value of the resistor PR5 is, therefore only of sufficient value so that its absence lowers the no-load speed of the motor LRM only a few revolutions per minute.

Under these conditions the motor will attempt to operate just slower than the speed of the strip leaves the drum it when the strip is Since the strip will leave the drum l6 at the desired speed or 120, the motor LRM will be turned faster than the setting of the field LRMf is set to operate the motor LRM and, therefore, the motor will regenerate power. This regenerated power will cause the coil 204 to rotate the arm 206 counterclockwise increasing the value of the resistance of element 208 in the circuit of the field LRMf decreasing the energization thereof and therefore the power regenerated. The relationship of this portion of the element 208 to the position of the arm 206 as determined by the coil 284 is such that a substantially constant predetermined amount of power is regenerated thereby putting a constant drag or tension on the strip being rolled.

As the speed of the drum I8 increases because of the lesser diameter of the strip being unwound therefrom, the speed of the motor LRM will increase. This increase in speed tends to cause more power to be regenerated thereby, but as the power increases, the coil 20 moves the arm 2% further in a counterclockwise direction still further reducing the strength of field LRM and maintaining its power output constant with a constant tension on the strip being unwound from the drum 18.

Referring to the regulator TRi, and the resistor FR4 associated therewith, as explained hereinbefore the normal strength of the field LCM; is adjusted to operate the motor LCM at the 400 speed which is used when the strip is being rolled from right to left and being wound on drum l8. When rolling from left to right under the same relative field excitation due to the action of the field LGc on the generator LG, the speed of motor LCM would be too slow and, therefore, the resistance FR was inserted to bring the speed up to that desired. Without the use of the regulator TRI, this would correctly describe the function and co-operation of the resistor FRA, however, as has just been seen in 

